Control device, control method, and non-transitory computer readable medium storing program

ABSTRACT

To provide a control device that can prevent an increase in a processing load and that can effectively allocate a radio resource. A control device (30) according the present disclosure includes: a deciding unit (31) configured to decide whether or not an interval between generation of a first flow that is generated when performing radio communication between a communication terminal (10) and a base station (20) and generation of a second flow that is generated after the generation of the first flow exceeds a permissible delay time of the first flow; and a determination unit (32) configured to determine deletion of non-transmitted data related to the communication terminal (10) after lapse of the permissible delay time of the first flow when it is decided that the generation interval exceeds the permissible delay time of the first flow.

TECHNICAL FIELD

The present disclosure relates a control device, a control method, and aprogram.

BACKGROUND ART

Currently, providing of ultra-low latency services via a mobile networkis being considered. The ultra-slow latency services may include, forexample, a self-driving service that transmits vehicle-mounted sensorinformation, traffic camera information, and map information etc. via amobile network.

A mobile carrier (or a mobile operator) needs to guarantee an SLA(Service Level Agreement) in order to provide the ultra-low latencyservices to a user. The SLA may, for example, stipulate the delay timeetc. to be guaranteed in the ultra-low latency service.

For example, Patent Literature 1 discloses that in order to maintainsatisfactory service quality, a radio resource is efficiently allocatedto a UE (User Equipment). Specifically, it discloses that allocation ofthe radio resource is optimized taking into account the informationrelated to the restriction in the delay of applications etc. In otherwords, Patent Literature 1 discloses that service quality is maintainedin a satisfactory state by optimizing the allocation of the radioresource so as not to have a base station exceed a permissible delaytime in providing an application service.

Further, Patent Literature 2 discloses processing of a packet bufferdevice discarding a packet that has arrived. Specifically, PatentLiterature 2 discloses that time during which the arrived packet isstagnant within a queue is estimated, and when the estimated timeexceeds a threshold value, the arrived packet is discarded without beingstored in the queue.

Further, Patent Literature 3 discloses that when the standby timeindicating the time taken from the reception of a packet to thetransmission thereof exceeds the maximum standby time, the packet isdiscarded. Further, Patent Literature 4 discloses that the packet thatis kept under the standby state in the queue is discarded when thestandby time exceeds the packet survival time.

CITATION LIST Patent Literature

Patent Literature 1: Published Japanese Translation of PCT InternationalPublication for Patent Application, No. 2014-522145

Patent Literature 2: International Patent Publication No. WO 2010/089886

Patent Literature 3: Japanese Unexamined Patent Application PublicationNo. 2000-286893

Patent Literature 4: Japanese Unexamined Patent Application PublicationNo. H11-289351

SUMMARY OF INVENTION Technical Problem

However, Patent Literature 1 does not disclose the processing performedby the base station when the amount of data to be transmitted becomeslarge and a packet that exceeds the permissible delay time whenproviding the application service is generated. Therefore, the basestation of Patent Literature 1 allocates a radio resource to the packetthat exceeds the permissible delay time when providing the applicationservice. As a result, there is a possibility that a problem of the radioresource that is allocated to the packet for which the permissible delaytime has not been exceeded becoming insufficient may arise.

Further, Patent Literatures 2 to 4 disclose that when the resident timeetc. exceeds a predetermined value for each packet, the packet that isto arrive or the packet within the queue is discarded. Therefore, whenmany packets exceeding the resident time etc. are present, it isnecessary to decide, for each packet, whether or not the packet needs tobe discarded, and thus the processing load of the device increases.

An object of the present disclosure is to provide a control device thatcan prevent an increase in a processing load and that can effectivelyallocate a radio resource, a control method, and a program.

Solution to Problem

A control device according to a first example aspect includes:

-   -   a deciding unit configured to decide whether or not an interval        between generation of a first flow that is generated when        performing radio communication between a communication terminal        and a base station and generation of a second flow that is        generated after the generation of the first flow exceeds a        permissible delay time of the first flow; and    -   a determination unit configured to determine deletion of        non-transmitted data related to the communication terminal after        lapse of the permissible delay time of the first flow when it is        decided that the generation interval exceeds the permissible        delay time of the first flow.

A control method according to a second example aspect includes:

-   -   deciding whether or not an interval between generation of a        first flow that is generated when performing radio communication        between a communication terminal and a base station and        generation of a second flow that is generated after the        generation of the first flow exceeds a permissible delay time of        the first flow; and    -   determining to delete non-transmitted data related to the        communication terminal after lapse of the permissible delay time        of the first flow when it is decided that the generation        interval exceeds the permissible delay time of the first flow.

A program according to a third aspect causes a computer to execute:

-   -   deciding of whether or not an interval between generation of a        first flow that is generated when performing radio communication        between a communication terminal and a base station and        generation of a second flow that is generated after the        generation of the first flow exceeds a permissible delay time of        the first flow; and    -   determination of deleting non-transmitted data related to the        communication terminal after lapse of the permissible delay time        of the first flow when it is decided that the generation        interval exceeds the permissible delay time of the first flow.

Advantageous Effects of Invention

According to the present disclosure, a control device that can preventan increase in a processing load and that can effectively allocate aradio resource, a control method, and a program are provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a structural diagram of a communication system according to afirst example embodiment;

FIG. 2 is a structural diagram of an MEC (Mobile Edge Computing) serveraccording to a second example embodiment;

FIG. 3 is diagram showing an outline of processing by a UE that hasreceived a discard message according to the second example embodiment;

FIG. 4 is a diagram showing a flow of transmission processing of adiscard message in an MEC server according to the second exampleembodiment;

FIG. 5 is a diagram showing a flow of processing when eNB receives adiscard message from the MEC server according to the second exampleembodiment;

FIG. 6 is a diagram showing a flow of data processing performed in theUE according to the second example embodiment;

FIG. 7 is a structural diagram of the UE according to a third exampleembodiment;

FIG. 8 is a structural diagram of the eNB according to each exampleembodiment;

FIG. 9 is a structural diagram of the UE according to each exampleembodiment; and

FIG. 10 is a structural diagram showing the MEC server according to eachexample embodiment.

DESCRIPTION OF EMBODIMENTS First Example Embodiment

Hereinbelow, an example embodiment according to the present disclosureis explained with reference to the drawings. A structural example of acommunication system according to a first example embodiment isexplained using FIG. 1. The communication system shown in FIG. 1includes a communication terminal 10, a base station 20, and a controldevice 30. The communication terminal 10, the base station 20, and thecontrol device 30 may be computer devices, the processing of which isperformed by causing a processor to execute a program stored in amemory.

The communication terminal 10 may be a mobile phone terminal, a smartphone terminal, or a tablet terminal. Further, the communicationterminal 10 may be an IoT (Internet of Things) terminal, a M2M (Machineto Machine) terminal, or an MTC (Machine Type Communication) terminal.The communication terminal 10 may be a UE (User Equipment) that is usedas a general term for a communication terminal in 3GPP (3rd GenerationPartnership Project).

The base station 20 performs radio communication with the communicationterminal 10. The base station 20 may be an eNB (an evolved Node B)defined as a base station that supports the radio communication standardLTE (Long Term Evolution) in the 3GPP. Alternatively, the base station20 may be Node B that supports the radio communication standardcorresponding to so-called 2G or 3G.

The control device 30 may be a server device that controls processingrelated to the radio communication between the communication terminal 10and the base station 20. For example, the control device 30 may be anMEC (Mobile Edge Computing) server. The MEC server may be disposed at aposition where it can perform directly communication with the basestation. The position where direct communication is possible is aposition where it is possible to perform communication without using acore network managed by a mobile carrier. For example, the MEC servermay be physically integrated with the base station. Alternatively, theMEC server may be disposed at the same building as the base station andconnected to an LAN (Local Area Network) within the building so that itcan perform communication with the base station. A transmission delaytime between the MEC server and a radio terminal can be shortened bylocating the MEC server in a vicinity of the base station. The MECserver is used, for example, for providing ultra-low latency applicationservices.

Next, a structural example of the control device 30 is explained. Thecontrol device 30 includes a deciding unit 31 and a determination unit32. The deciding unit 31 and the determination unit 32 may each be asoftware or a module, the processing of which is executed by causing aprocessor to execute a program stored in a memory. Further, the decidingunit 31 and the determination unit 32 may be a hardware such as a chipor a circuit etc.

The deciding unit 31 decides whether or not an interval betweengeneration of a first flow that is generated when the communicationterminal 10 and the base station 20 perform radio communication andgeneration of a second flow that is generated after the generation ofthe first flow exceeds a permissible delay time of the first flow.

The flow that is generated when performing the radio communicationincludes, for example, one or a plurality of data transmitted in theapplication service provided to the communication terminal 10. Further,the data included in the flow may be referred to as data packets. Theflow related to the communication terminal 10 may be a flow oftransmission from the communication terminal 10 to the base station 20or a flow of transmission from the base station 20 to the communicationterminal 10. Alternatively, the flow that is generated when performingthe radio communication may include, for example, a flow of transmissionfrom the communication terminal 10 to the base station 20 and a flow oftransmission from the base station 20 to the communication terminal 10.Data included in the flow of transmission from the communicationterminal 10 to the base station 20 is collectively referred to as UL(Uplink) data. Further, data included in the flow of transmission fromthe base station 20 to the communication terminal 10 is collectivelyreferred to as DL (Downlink) data. Data transmitted in the applicationservice (for example, application data) may be, for example, image dataor motion image data. Further, the application data may include arequest message that requests transmission of image data etc., aresponse message that responds to the request message, and the like.

An interval between generations of the flows may be from when the dataincluded in the flow of data that should be transmitted is stored in abuffer in the communication terminal 10 or the base station 20 untilwhen the data included in a next flow of data that should be transmittedis stored in the buffer. Alternatively, the interval between generationsof the flows may be time from creation of the data included in a flow ofdata that should be transmitted by the application until creation ofdata that is included in the next flow of data to be transmitted.

The deciding unit 31 may calculate the interval between generations ofthe flows by subtracting the time of generation of the first flow fromthe time of generation of the second flow. Alternatively, the decidingunit 31 may start a timer when the first flow is generated and stop thetimer when the second flow is generated and specify the period duringwhich the timer is activated as the interval between generations offlows. Alternatively, when the application has predetermined theinterval between generations of the flows in advance, the deciding unit31 may acquire information related to the interval between generationsof the flows from the application.

The permissible delay time means a period during which transmission of aplurality of data packets included in one flow should be completed. Thepermissible delay time is requested by the application. The permissibledelay time may also be referred to as transmission time limit.Alternatively, the permissible delay time can be referred to as themaximum transmission delay time permitted by the application. Thepermissible delay time can be defined variously. For example, thepermissible delay time may indicate completion deadline of transmissionby a sender of an application layer. Alternatively, the permissibledelay time may indicate completion deadline of transmission by a senderof a radio layer. Alternatively, the permissible delay time may indicatecompletion deadline of reception by a receiver of the application layer.Alternatively, the permissible delay time may indicate completiondeadline of reception by a receiver of the radio layer. Alternatively,to be more specific, the permissible delay time may indicate thedeadline from the start of transmission of a first data packet relatedto one flow by the sender of the application layer to the completion ofreception of a last data packet related to one flow by the receiver ofthe application layer. Alternatively, the permissible delay time mayindicate the deadline from the start of transmission of a first datapacket related to one flow by the sender of the radio layer to thecompletion of reception of a last data packet related to one flow by thereceiver of the radio layer.

Further, the permissible delay time may also be referred to as atransmission deadline or simply as a deadline.

The deciding unit 31 may receive information relate to the permissibledelay time from the application included in the control device 30.

The determination unit 32 determines to delete the non-transmitted datarelated to the communication terminal 10 when it is decided in thedeciding unit 31 that the interval between generations of the first flowand the second flow generated after the first flow exceeds thepermissible delay time of the first flow. The non-transmitted data maybe, for example, data related to the communication terminal 10 which hasnot been transmitted after lapse of the first permissible delay time.The non-transmitted data related to the communication terminal 10 may bethe UL data transmitted from the communication terminal 10 to the basestation 20, and may be the DL data transmitted from the base station 20to the communication terminal 10.

As described above, the control device 30 can perform the processingmentioned below when the interval between generations of the flows thatare generated when performing radio communication exceeds thepermissible delay time of the first flow, which is a flow generatedfirst. The control device 30 can determine to delete the non-transmitteddata related to the communication terminal 10 after lapse of thepermissible delay time of the first flow.

When the interval between generations of the flows exceeds thepermissible delay time of the first flow, the second flow is notincluded in the non-transmitted data related to the communicationterminal 10 after lapse of the permissible delay time of the first flowand before the generation of the second flow. Therefore, even if thenon-transmitted data related to the communication terminal 10 afterlapse of the permissible delay time of the first flow is deleted, onlythe data included in the first flow is deleted.

Since the permissible delay time of the first flow has already lapsed,the communication terminal 10 or the base station 20 discards thereceived data even if the communication terminal 10 or the base station20 receives the data relates to the first flow. The control device 30can determine to delete the non-transmitted data of the communicationterminal 10 or the base station 20 before a radio resource is allocatedto the data related to the first flow for which the permissible delaytime has already lapsed.

As a result, it is possible to prevent the radio resource from beingallocated to the data related to the first flow for which thepermissible delay time has already lapsed between the communicationterminal 10 and the base station 20.

Further, the deciding unit 31 does not perform the deciding processingfor each packet but can perform the deciding processing for each flowthat includes a plurality of data or packets. In other words, thedetermination unit 32 does not determine whether or not to discard datafor each packet but determines whether or not to collectively discard aplurality of data or packets included in the flow. Therefore, aprocessing load in the deciding unit 31 can be reduced when the decidingprocessing is performed for each packet.

Further, in the first example embodiment, a configuration in which thecontrol device 30 is a device different from the communication terminal10 and the base station 20 has been explained. However, thecommunication device 10 and the base station 20 may include the controldevice 30. In other words, the communication terminal 10 and the basestation 20 may include the deciding unit 31 and the determination unit32 which are included in the control device 30.

Second Example Embodiment

Next, a structural example of an MEC server 40 according to a secondexample embodiment is explained using FIG. 2. The MEC server 40corresponds to the control device 30 shown in FIG. 1. The MEC server 40has a configuration in which a communication unit 41 and a managementunit 42 are added to the control device 30 shown in FIG. 1. Detailedexplanations of the function and the operation of the deciding unit 31and the determination unit 32 that are the same as those of FIG. 1 areomitted. The communication unit 41 and the management unit 42 may eachbe a software or a module, the processing of which is executed bycausing a processor to execute a program stored in a memory. Further,the communication unit 41 and the management unit 42 may be a hardwaresuch as a chip or a circuit etc.

Further, in the following explanation, the communication terminal 10shown in FIG. 1 is explained as a UE 50. Further, the base station 20shown in FIG. 1 is explained as an eNB 60.

The management unit 42 manages information related to the permissibledelay time of a flow that is generated when the UE 50 and the eNB 60perform radio communication. The management unit 42 may manageinformation related to permissible delay input by an administrator etc.of the MEC server 40, and may manage information related to thepermissible delay received from application server etc. The informationrelated to the permissible delay may, for example, be associated withthe application service provided to the UE. In other words, theinformation related to the permissible delay may be defined for eachapplication. Alternatively, the information related to the permissibledelay may be defined for each UE.

The deciding unit 31 measures an interval between generations of theflows. For example, the deciding unit 31 may receive a messageindicating that a flow is generated from the UE 50 or the eNB 60. Thedeciding unit 31 may specify the interval between generations of theflows by measuring an interval between messages. The message indicatinggeneration of a flow may be, for example, a message or U(User)-Planedata in an application layer or may be a control message orC(Control)-Plane data. The U-Plane data is data referred to as user datain the mobile network and C-Plane data is data referred to as controlinformation.

Alternatively, the deciding unit 31 may acquire information related tothe interval between generations of the flows from the application whenthe interval between generations of the flows is determined in advancein the application within the MEC server 40 or the application withinthe application server. The information related to the interval betweengenerations of the flows determined in advance in the application may bemanaged by the management unit 42.

The communication unit 41 transmits a message to the UE 50 and the eNB60 when the permissible delay time of the first flow generated by radiocommunication between the UE 50 and the eNB 60 is exceeded in thedetermination unit 32. For example, the communication unit 41 transmitsa discard message including identification information of the UE 50 tothe eNB 60 when it is determined that the non-transmitted data relatedto the UE 50 is to be deleted. Further, the eNB 60 transmits, to the UE50, a discard message including the identification information of the UE50. That is, the MEC server 40 transmits the discard message includingthe identification information of the UE 50 to the UE 50 via the eNB 60.

Further, the communication unit 41 transmits the discard message to theeNB 60 when it is determined that the non-transmitted data related tothe UE 50 is to be deleted. The discard message includes informationindicating that the non-transmitted data to the UE 50 is the object ofdeletion. Further, the communication unit 41 transmits the discardmessage to the UE 50 via the eNB 60. The discard message includesinformation indicating that the non-transmitted data to the eNB 60 isthe object of deletion.

Further, the deciding unit 31 or the determination unit 32 may managethe states of the buffers in the UE 50 and the eNB 60. For example, thedeciding unit 31 and the determination unit 32 may receive informationrelated to the states of the buffers from the UE 50 and the eNB 60 viathe communication unit 41 periodically or irregularly. The state of thebuffer may be, for example, whether or not the non-transmitted data ispresent within the buffer, or the amount of non-transmitted data presentwithin the buffer. Further, the determination unit 32 may transmit amessage indicating that the data within the buffer is cleared to the UE50 or the eNB 60 when it is decided that the non-transmitted data ispresent within the buffer of the UE 50 or the eNB 60 after lapse of thepermissible delay time. The determination unit 32 may transmit a messageinstructing to clear the data within the buffer to the UE 50 or the eNB60 via the communication unit 41.

Next, an outline of the processing performed in the UE 50 that hasreceived the discard message is explained using FIG. 3. FIG. 3 showsdata stored in the buffer at times t1 to t6. Note that herein, theoutline of the processing performed in the UE 50 is explained using FIG.3, and the same processing as that shown in FIG. 3 is performed in theeNB 60.

At the time t1, Flow#A transmitted from the UE 50 to the eNB 60 isgenerated. In FIG. 3, it is indicated that the transmission data isstored in the buffer at the time t1. A shaded area shown in FIG. 3indicates the transmission data. The transmission data is data includedin Flow#A.

Next, at the time t2, the data is transmitted from the UE 50 to the eNB60 whereby the data stored in the buffer is reduced compared to that atthe time t1.

Next, the time t3 indicates the permissible delay time (deadline) ofFlow#A. The time t4 is a time after lapse of the permissible delay timeof Flow#A and indicates that the non-transmitted data is still presentwithin the buffer after lapse of the permissible delay time of Flow#A.

Here, it is assumed that the UE 50 receives a discard message from theMEC server 40 via the eNB 60. Therefore, at the time t5, the UE 50clears or deletes the non-transmitted data still present within thebuffer after lapse of the permissible delay time. In FIG. 3, it isindicated that since the data within the buffer of the UE 50 is clearedat the time t5, the non-transmitted data related to Flow#A is notpresent within the buffer. The time t5 is a timing after lapse of thepermissible delay time of Flow#A and before generation of Flow#B.

Next, at the time t6, Flow#B transmitted from the UE 50 to the eNB 60 isgenerated. In FIG. 3, it is indicated that the transmission data isstored in the buffer at the time t6.

The interval between generation of Flow#A and Flow#B exceeds thepermissible delay time of Flow#A. Therefore, the non-transmitted datastill present within the buffer at the time t4 is the data related toFlow#A and does not include the data related to Flow#B. Therefore, theUE 50 can delete only the data related to Flow#A at the time t5.

Next, a flow of transmission processing of the discard message in theMEC server 40 according to the second example embodiment is explainedusing FIG. 4. First, the deciding unit 31 obtains the permissible delaytime of the flow of data from the management unit 42 (Step S11). Theflow is, for example, a flow that is generated when the UE 50 and theeNB 60 perform radio communication. For example, in Step S11, thepermissible delay time related to the flow of transmission from the UE50 to the eNB 60 is obtained. Each time a flow is generated, thedeciding unit 31 may obtain the permissible delay time related to theflow. Alternatively, when the permissible delay time of the flow relatedto a specific application is the same for all applications, the decidingunit 31 may obtain the permissible delay time related to the flow onlyat a timing at which the first flow is generated.

Next, the deciding unit 31 measures the interval between the generationsof the flows of transmission from the UE 50 to the eNB 60 (Step S12).When the interval between generations of the flows is determined inadvance, the deciding unit 31 acquires information related to theinterval between generations of the flows determined in advance from theapplication in the UE 50 or the application in the application server.The application server may be a device different from the UE 50.

Next, the deciding unit 31 decides whether or not the interval betweengenerations of the flows related to the UE 50 has exceeded thepermissible delay time (Step S13). When the deciding unit 31 decidesthat the interval between generations of the flows related to the UE 50exceeds the permissible delay time, the determination unit 32 determinesto delete the non-transmitted data after lapse of the permissible delaytime of the flow that is generated in the UE 50. Further, thecommunication unit 41 transmits the discard message including theidentification information of the UE 50 to the UE 50 via the eNB 60(Step S14).

In Step S13, when the deciding unit 31 decides that the interval betweengenerations of the flows related to the UE 50 has not exceeded thepermissible delay time, the processing ends.

Next, a flow of processing when the eNB 60 according to the secondexample embodiment receives a discard message from the MEC server 40 isexplained using FIG. 5. Firstly, the eNB 60 receives the discard messagetransmitted from the MEC server 40 (Step S21). It is assumed that theidentification information of the UE 50 is included in the discardmessage received by the eNB 60.

Next, the eNB 60 transmits the discard message received from the MECserver 40 to the UE 50 (Step S22). The eNB 60 transmits the discardmessage to the UE indicated by the identification message included inthe discard message received from the MEC server 40.

Next, the flow of data processing performed in the UE 50 according tothe second example embodiment is explained using FIG. 6. First, the UE50 receives the discard message transmitted from the eNB 60 (S31).

Next, the UE 50 decides whether or not the permissible delay time of thetarget flow has lapsed in the discard message (Step S32). The targetflow in the discard message is the flow including the data which is tobe transmitted to the eNB 60 by the UE 50.

The permissible delay time of the flow may be, for example, notified tothe UE 50 in advance based on the SLA. For example, the UE 50 mayacquire information related to the permissible delay time from the MECserver 40 or the application server etc. in advance prior to getting aservice related to the target flow in the discard message.Alternatively, the discard message received from the MEC server 40 viathe eNB 60 may include the information related to the permissible delaytime of the flow.

The UE 50 decides whether or not the non-transmitted data is presentwithin the buffer when it decides that the permissible delay time of thetarget flow in the discard message has lapsed (Step S33). The UE 50clears the data within the buffer when it decides that thenon-transmitted data is present within the buffer (Step S34). In otherwords, the UE 50 discards or deletes all of the data within the bufferwhen it decides that the non-transmitted data is present within thebuffer.

When it is decided that the permissible delay time has not lapsed inStep S32 and when it is decided that the non-transmitted data is notpresent in Step S33, the UE 50 repeats the processing subsequent to Step32.

Further, the flow of data processing performed in UE 50 has beenexplained using FIG. 6, and the same data processing is performed in eNB60. The eNB 60 can recognize that the target flow in the discard messageis the flow including the data which is transmitted to the UE 50 sincethe discard message includes the identification information of the UE50. Therefore, in the eNB 60 as well, by performing the processing inSteps S31 to S34 of FIG. 6, the non-transmitted data within the bufferrelated to the UE 50 can be cleared.

Further, the eNB 60 can perform radio communication with a plurality ofUEs. Therefore, the eNB 60 uses a different butter for each UE.Accordingly, the eNB 60 specifies which UE's buffer to deletenon-transmitted data included in after the Step S31 shown in FIG. 6.

As described above, the MEC server 40 according to the second exampleembodiment can determine to delete the non-transmitted data after lapseof the permissible delay time of the flow related to the UE 50 when theinterval between generations of the flows in the UE 50 exceeds thepermissible delay time. As a result, it is possible to preventallocation of a radio resource to the non-transmitted data after lapseof the permissible delay time of the flow.

Further, it is possible to prevent coresidence of the data for which thepermissible delay time of the flow has not been exceeded and the datafor which the permissible delay time of the flow has been exceededwithin the buffer by targeting the flow whose generation interval hasexceeded the permissible delay time. As a result, it is possible toclear only the data for which the permissible delay time of the flow hasbeen exceeded when the non-transmitted data within the buffer iscleared. By this configuration, it is possible to prevent lowering ofthe data arrival rate by discarding the data for which the permissibledelay time of the flow has not been exceeded.

Further, in the aforementioned explanation, the processing of deletingthe non-transmitted data within the buffer after lapse of thepermissible delay time by the UE 50 and the eNB 60 has been explained.However, the UE 50 and the eNB 60 may delete the non-transmitted datawithin the buffer before the permissible delay time. The UE 50 and theeNB 60 delete the non-transmitted data present within the buffer priorto the permissible delay time by a prescribed time. As a result, the UE50 and the eNB 60 may delete the data that could, in the future, becomenon-transmitted data after lapse of the permissible delay time. Further,the UE 50 and the eNB 60 may delete the non-transmitted data that ispresent within the buffer when the non-transmitted data present withinthe buffer exceeds the threshold value of the predetermined data amountprior to the permissible delay time by a prescribed time.

Third Example Embodiment

Next, a structural example of a UE 70 according to a third exampleembodiment is explained using FIG. 7. In the second example embodiment,an example of determining the target UE in which the non-transmitteddata after lapse of the permissible delay time of the flow is deleted bythe MEC server 40 has been explained. In the third example embodiment,the UE 70 determines whether or not the UE 70 itself is the UE for whichthe non-transmitted data after lapse of the permissible delay time ofthe flow is the target of deletion.

The UE 70 includes a deciding unit 71, a determination unit 72, acommunication unit 73, a management unit 74, and a processing unit 75.The deciding unit 71, the determination unit 72, and the management unit74 are the same as the deciding unit 31, the determination unit 32, andthe management unit 42 of the MEC server 40 in FIG. 2, and thus detailedexplanations thereof are omitted.

In FIG. 7, the deciding unit 71 decides whether or not the intervalbetween generations of the flows that are generated when performingradio communication with the eNB 60 exceeds the permissible delay timeof the flow. There is a case where the interval between generations ofthe flows that are generated when performing radio communication withthe eNB 60 exceeds the permissible delay time of the flow. In this case,the determination unit 72 determines to delete the non-transmitted datawhich has not been transmitted to the eNB 60 after lapse of thepermissible delay time.

The communication unit 73 transmits a discard message to the eNB 60 whenit is determined in the determination unit 72 that non-transmitted dataafter lapse of the permissible delay time is to be discarded. Thediscard message includes identification information of the UE 70. Thediscard message is used to instruct or request the eNB 60 to discard thenon-transmitted data for the flow related to the UE 70 when thenon-transmitted data is present after lapse of the permissible delaytime.

Further, the communication unit 73 allocates a radio resource to thedata stored within the buffer of the UE 70 and transmits the data to theeNB 60. The buffer within the UE 70 may, for example, include theprocessing unit 75.

The processing unit 75 discards the non-transmitted data within thebuffer after lapse of the permissible delay time when it is determinedin the determination unit 72 that the non-transmitted data after lapseof the permissible delay time is to be discarded.

When the eNB 60 receives the discard message from the UE 70, it clearsthe non-transmitted data within the buffer related to the UE 70.

Further, in the third example embodiment, it has been explained that theUE 70 determines whether or not the UE 70 itself is the UE for which thenon-transmitted data after lapse of the permissible delay time is thetarget of deletion. Alternatively, the eNB 60 may determine the UE forwhich the non-transmitted data after lapse of the permissible delay timeof the flow is the target of deletion. The eNB 60 transmits the discardmessage to the UE 70 when it determines to discard the non-transmitteddata after lapse of the permissible delay time of the flow related tothe UE 70. Further, the UE 70 follows the discard message and discardsthe non-transmitted data after lapse of the permissible delay time ofthe flow.

As described above, the UE 70 according to the third example embodimentcan determine whether or not to discard the non-transmitted data afterlapse of the permissible delay time of the flow. Accordingly, the MECserver 40 does not need to transmit the discard message to the UE 70 viathe eNB 60. Therefore, it is possible to reduce the processing load ofthe MEC server 40 and further, to prevent allocation of the radioresource for transmitting the discard message.

Further, when the eNB 60 determines whether or not the non-transmitteddata after lapse of the permissible delay time of the flow is to bediscarded, it is also possible to reduce the processing load of the MECserver 40.

Fourth Example Embodiment

Next, an example of an operation of the MEC server 40 according to afourth example embodiment is explained. In the fourth exampleembodiment, an operation of the MEC server 40 when the data for whichthe permissible delay time of the flow has been exceeded and the datafor which the permissible delay time of the flow has not been exceededare coresident in a buffer included in the UE 50 or the eNB 60 isexplained.

For example, there may be a case where the non-transmitted data of theflow related to the UE 50 was not the target of deletion, but at a laterstage, the non-transmitted data of the flow related to the UE 50 becamethe target of deletion. In this case, the data for which the permissibledelay time of the flow has been exceeded and the data for which thepermissible delay time of the flow has not been exceeded may becoresident within the buffer.

Specifically, there is case where at least one of the permissible delaytime and the interval between generations of the flows changes after itis decided that the non-transmitted data of the flow related to the UE50 is not the target of deletion. In this case, the non-transmitted dataof the flow related to the UE 50 may be re-decided as being the targetof deletion.

Alternatively, when the MEC server 40 has a measurement period formeasuring the flow generation interval set, the non-transmitted data ofthe flow related to the UE 50 is not the target of deletion in themeasurement period, and the non-transmitted data of the flow related tothe UE 50 becomes the target of deletion after lapse of the measurementperiod.

In view of the aforementioned circumstances, when the data for which thepermissible delay time of the flow has been exceeded and the data forwhich the permissible delay time of the flow has not been exceeded arecoresident in the buffer included in the UE 50 or the eNB 60, whether toclear the data within the buffer may be decided based on variouscriterions.

For example, the MEC server 40 may decide whether or not to clear thedata within the buffer according to the data stored in the bufferincluded in the UE 50 or the eNB 60. Specifically, the MEC server 40 mayclear the data within the buffer when the amount of data for which thepermissible delay time of the flow has been exceeded exceeds the amountof data for which the permissible delay time of the flow has not beenexceeded. Further, the MEC server 40 may clear the data within thebuffer when the number of flows for which the permissible delay time hasbeen exceeded exceeds the number of flows for which the permissibledelay time has not been exceeded. Further, the MEC server 40 may notclear the data within the buffer when the amount of data for which thepermissible delay time of the flow has been exceeded falls short of theamount of data for which the permissible delay time of the flow has notbeen exceeded. Further, the MEC server 40 may clear the data within thebuffer when the number of flows for which the permissible delay time hasbeen exceeded falls short of the number of flows for which thepermissible delay time has not been exceeded.

Alternatively, the MEC server 40 may clear all of the data within thebuffer when the data for which the permissible delay time of the flowhas been exceeded and the data for which the permissible delay time ofthe flow has not been exceeded are coresident in the buffer in the UE 50or the eNB 60. Alternatively, there is a case where the data for whichthe permissible delay time of the flow has been exceeded and the datafor which the permissible delay time of the flow has not been exceededare coresident in the buffer included in the UE 50 or the eNB 60. Inthis case, the MEC server 40 may not clear all of the data within thebuffer.

As described above, it is possible to determine in advance how the datawithin the buffer is handled when the data for which the permissibledelay time of the flow has been exceeded and the data for which thepermissible delay time of the flow has not been exceeded are coresidentwithin the buffer of the UE50 or the eNB 60.

Further, in the fourth example embodiment, the operation of the MECserver 40 has been explained, however, the same operation may beperformed by the UE 50 or the eNB 60.

Next, structural examples of the MEC server 40, the UE 50, the eNB 60,and the UE 70 explained in the plurality of aforementioned exampleembodiments are explained. FIG. 8 is a block diagram showing astructural example of the eNB 60. Referring to FIG. 8, the eNB 60includes an RF transceiver 1001, a network interface 1003, a processor1004, and a memory 1005. The RF transceiver 1001 performs analogue RFsignal processing for communicating with the UEs. The RF transceiver1001 may include a plurality of transceivers. The RF transceiver 1001 iscoupled to an antenna 1002 and the processor 1004. The RF transceiver1001 receives a modulation symbol data (or an OFDM symbol data) from theprocessor 1004, generates a transmission RF signal, and supplies thetransmission RF signal to the antenna 1002. Further, the RF transceiver1001 generates a baseband reception signal based on the reception signalRF received by the antenna 1002 and supplies the signal to the processor1004.

The network interface 1003 is used for communicating with the networknode (e.g., other core network node). The network interface 1003 mayinclude, for example, a network interface card (NIC) pursuant to theIEEE 802.3 series.

The processor 1004 performs data plane processing and control planeprocessing including digital baseband signal processing for radiocommunication. For example, in the case of the LTE standard or the 5Gstandard, the digital baseband signal processing by the processor 1004may include signal processing of an MAC layer and a PHY layer.

The processor 1004 may include a plurality of processors. For example,the processor 1004 may include a modem processor (e.g., DSP) thatperforms digital baseband signal processing and a protocol stackprocessor (e.g., CPU or MPU) that performs control plane processing.

The memory 1005 is configured by a combination of a volatile memory anda non-volatile memory. The memory 1005 may include a plurality of memorydevices that are physically independent. The non-volatile memory is, forexample, a Static Random Access Memory (SRAM), a Dynamic RAM (DRAM), ora combination thereof. The non-volatile memory is a Mask Read OnlyMemory (MROM), an Electrically Erasable Programmable ROM (EEPROM), aflash memory, or a hard disk drive, or a combination thereof. The memory1005 may include a storage disposed at a distance from the processor1004. In this case, the processor 1004 may access the memory 1005 viathe network interface 1003 or the I/O interface (not shown).

The memory 1005 may store a software module (a computer program)including an instruction group and data for performing processing by theeNB 60 described in the aforementioned plurality of example embodiments.In some implementations, the processor 1004 may be configured so thatthe processing by the eNB 60 explained above is performed by reading outthe software module from the memory 1005.

FIG. 9 is a block diagram showing a structural example of the UE 50 andthe UE 70. A Radio Frequency (RF) transceiver 1101 performs analogue RFsignal processing for performing communication with the eNB 60. Theanalogue RF signal processing performed by the RF transceiver 1101includes frequency up-conversion, frequency down-conversion,amplification. The RF transceiver 1101 is coupled to an antenna 1102 anda baseband processor 1103. That is, the RF transceiver 1101 receives themodulation symbol data (or OFDM symbol data) from the baseband processor1103, generates the transmission RF signal, and supplies thetransmission RF signal to the antenna 1102. Further, the RF transceiver1101 generates the baseband reception signal based on the RF signalreceived by the antenna 1102 and supplies the generated signal to thebaseband processor 1103.

The baseband processor 1103 performs the digital baseband signalprocessing (the data plane processing) and the control plane processing.The digital baseband signal processing includes (a) datacompression/recovery, (b) data segmentation/concatenation, (c)formation/decomposition of transmission format (data stream), (d)encoding/decoding of transmission path, (e) modulation (symbol mapping),and (f) generation of OFDM symbol data (the baseband OFDM signal) by theInverse Fast Fourier Transform(IFFT)etc. On the other hand, the controlplane processing includes communication management of a layer 1 (e.g.,transmission power control), a layer 2 (e.g., a radio resourcemanagement and hybrid automatic repeat request (HARQ) processing), and alayer 3 (e.g., attach, mobility, and communication management related tosignaling).

For example, in the case of the LTE standard and the 5G standard, thedigital baseband signal processing by the baseband processor 1103 mayinclude a Packet Data Convergence Protocol (PDCP) layer, a Radio LinkControl (RLC) layer, a MAC layer, and a PHY layer. Further, the controlplane processing by the baseband processor 1103 may include a Non-AccessStratum(NAS) protocol, an RRC protocol, and processing of MAC CE.

The baseband processor 1103 may include a modem processor (e.g., DigitalSignal Processor (DSP)) that performs the digital baseband signalprocessing and a protocol stack processor (e.g., Central Processing Unit(CPU) or a Micro Processing Unit (MPU) that performs processing ofcontrol plane processing. In this case, the protocol stack processorthat performs the control plane processing may be a common part as anapplication processor 1104 described later.

The application processor 1104 may also be referred to as a CPU, an MPU,a microprocessor, or a processor core. The application processor 1104may include a plurality of processors (a plurality of processor cores).The application processor 1104 realizes various function of the UE 50and the UE 70 by executing a system software program (Operating System(OS)) and various application programs (for example, a communicationapplication, a WEB browser, a mailer, a camera operation application, amusic playback application) read out from the memory 1106 and a memory(not shown).

In some implementations, as shown by the dotted lines (1105) in FIG. 9,the baseband processor 1103 and the application processor 1104 may beintegrated on one chip. In other words, the baseband processor 1103 andthe application processor 1104 may be mounted on one System on Chip(SoC) device 1105. The SoC device may also be referred to as a systemLarge Scale Integration (LSI) or a chip set.

The memory 1106 may be a volatile memory or a non-volatile memory, or acombination thereof. The memory 1106 may include a plurality of memorydevices that are physically independent. The non-volatile memory is, forexample, a Static Random Access Memory (SRAM), a Dynamic RAM (DRAM), ora combination thereof. The non-volatile memory is a Mask Read OnlyMemory (MROM), an Electrically Erasable Programmable ROM (EEPROM), aflash memory, or a hard disk drive, or a combination thereof. Forexample, the memory 1106 may include the baseband processor 1103, theapplication processor 1104, and an external memory device that isaccessible from the SoC device 1105. The memory 1106 may include abuilt-in memory device integrated within the baseband processor 1103,the application processor 1104, or the SoC device 1105. Further, thememory 1106 may include a memory within a Universal Integrated CircuitCard (UICC).

The memory 1106 may store a software module (a computer program)including an instruction group and data for performing processing by theUE 50 and the UE 70 described in the aforementioned plurality of exampleembodiments. In some implementations, the processor 1103 and theapplication processor 1104 may be configured so that the processing bythe UE 50 and the UE 70 explained in the aforementioned exampleembodiments are performed by reading out the software module from thememory 1106.

FIG. 10 is a block diagram showing a structural example of the MECserver 40. Referring to FIG. 10, the MEC server 40 include a networkinterface 1201, a processor 1202, and a memory 1203. The networkinterface 1201 is used for communicating with another network nodedevice that configures the communication system. The network interface1201 may include, for example, a network interface card (NIC) pursuantto the IEEE 802.3 series.

The processor 1202 may be configured so that the processing by the MECserver 40 explained in the aforementioned example embodiments usingsequence diagrams and flowcharts is performed by reading out thesoftware (a computer program) from the memory 1203. The processor 1202may be, for example a microprocessor, an MPU (Micro Processing Unit), ora CPU (Central Processing Unit). The processor 1202 may include aplurality of processors.

The memory 1203 is configured by a combination of a volatile memory anda non-volatile memory. The memory 1203 may include a storage disposed ata distance from the processor 1202. In this case, the processor 1202 mayaccess the memory 1203 via the I/O interface (not shown).

In the example shown in FIG. 10, the memory 1203 is used to store agroup of software group modules. The processor 1202 may be configured sothat the processing by the MEC server 40 explained in the aforementionedexample embodiments is performed by reading out the software modulesfrom the memory 1203.

As explained using FIG. 10, each of the processors included in the MECserver 40 may be configured to execute one or a plurality or programsincluding an instruction group for casing a computer to execute thealgorithms explained using the figures.

The program can be stored and provided to a computer using any type ofnon-transitory computer readable media. Non-transitory computer readablemedia include any type of tangible storage media. Examples ofnon-transitory computer readable media include magnetic storage media(such as floppy disks, magnetic tapes, hard disk drives, etc.), opticalmagnetic storage media (e.g. magneto-optical disks), CD-ROM (compactdisc read only memory), CD-R (compact disc recordable), CD-R/W (compactdisc rewritable), and semiconductor memories (such as mask ROM, PROM(programmable ROM), EPROM (erasable PROM), flash ROM, RAM (random accessmemory), etc.). The program may be provided to a computer using any typeof transitory computer readable media. Examples of transitory computerreadable media include electric signals, optical signals, andelectromagnetic waves. Transitory computer readable media can providethe program to a computer via a wired communication line (e.g. electricwires, and optical fibers) or a wireless communication line.

Note that the present disclosure is not limited to the aboveembodiments, and can be naturally changed variously without departingfrom the gist of the disclosure.

The present disclosure has been described above with reference to theexample embodiments. However, the present disclosure is not limited tothereto. The structure and the details of the present disclosure can bemodified in various ways within the spirit and scope of the presentdisclosure that can be understood by a skilled person in the art.

This application is based upon and claims the benefit of priority fromJapanese patent application No. 2017-217495, filed on Nov. 10, 2017, thedisclosure of which is incorporated herein in its entirety by reference.

The whole or part of the example embodiments disclosed above can bedescribed as, but not limited to, the following supplementary notes.

(Supplementary Note 1)

A control device comprising:

-   -   a deciding unit configured to decide whether or not an interval        between generation of a first flow that is generated when        performing radio communication between a communication terminal        and a base station and generation of a second flow that is        generated after the generation of the first flow exceeds a        permissible delay time of the first flow; and    -   a determination unit configured to determine deletion of        non-transmitted data related to the communication terminal after        lapse of the permissible delay time of the first flow when it is        decided that the generation interval exceeds the permissible        delay time of the first flow.

(Supplementary Note 2)

The control device described in Supplementary note 1, wherein thedeciding unit measures the generation interval.

(Supplementary Note 3)

The control device described in Supplementary note 1 or 2 furthercomprising a management unit configured to manage information related topermissible delay times of the first flow and the second flow, whereinthe determination unit obtains the permissible delay time of the firstflow from the management unit.

(Supplementary Note 4)

The control device described in any one of Supplementary notes 1 to 3,wherein the determination unit determines deletion of data remaining ina buffer configured to store data included in the first flow and thesecond flow after lapse of the permissible delay time of the first flow.

(Supplementary Note 5)

The control device described in any one of Supplementary notes 1 to 4,wherein the deciding unit re-decides whether or not the generationinterval exceeds the permissible delay time when at least one of thegeneration interval and the permissible delay time of the first flow ischanged.

(Supplementary Note 6)

The control device described in any one of Supplementary notes 1 to 5further comprising a communication unit configured to transmitinformation indicating that the non-transmitted data related to thecommunication terminal after lapse of the permissible delay time of thefirst flow is deleted to the communication terminal and the basestation.

(Supplementary Note 7)

The control device described in Supplementary note 6, wherein thecommunication unit transmits the information indicating that thenon-transmitted data is deleted to the communication terminal, thedestination of the information being the base station, and transmits theinformation indicating that the non-transmitted data is deleted to thebase station, the destination of the information being the communicationterminal.

(Supplementary Note 8)

The control device described in Supplementary note 6 or 7, wherein thedeciding unit detects presence of the non-transmitted data related tothe communication terminal after lapse of the permissible delay time ofthe first flow, and the communication unit instructs the communicationterminal or the base station that has the non-transmitted data to deletethe non-transmitted data.

(Supplementary Note 9)

The control device described in any one of Supplementary notes 1 to 5further comprising data a data processing unit configured to delete thenon-transmitted data related to the communication terminal after lapseof the permissible delay time of the first flow.

(Supplementary Note 10)

The control device described in Supplementary note 9, wherein the dataprocessing unit deletes the non-transmitted data at a prescribed timingbefore lapse of the permissible delay time of the first flow.

(Supplementary Note 11)

A control method comprising:

-   -   deciding whether or not an interval between generation of a        first flow that is generated when performing radio communication        between a communication terminal and a base station and        generation of a second flow that is generated after the        generation of the first flow exceeds a permissible delay time of        the first flow; and    -   determining to delete non-transmitted data related to the        communication terminal after lapse of the permissible delay time        of the first flow when it is decided that the generation        interval exceeds the permissible delay time of the first flow.

(Supplementary Note 12)

The control method described in Supplementary note 11, furthercomprising measuring the generation interval between the first flow andthe second flow used in the deciding.

(Supplementary Note 13)

The control method described in Supplementary note 11 or 12, furthercomprising re-deciding whether or not the generation interval exceedsthe permissible delay time when at least one of the generation intervaland the permissible delay time of the first flow is changed.

(Supplementary Note 14)

The control method described in any one of Supplementary notes 11 to 13,further comprising transmitting, after it is determined that thenon-transmitted data related to the communication terminal after lapseof the permissible delay time of the first flow is deleted, informationof the determination to the communication terminal and the base station.

(Supplementary Note 15)

The control method described in any one of Supplementary notes 11 to 13,further comprising deleting, after it is determined that thenon-transmitted data related to the communication terminal after lapseof the permissible delay time of the first flow is deleted, thenon-transmitted data related to the communication terminal after lapseof the permissible delay time of the first flow.

(Supplementary Note 16)

A program for causing a computer to execute:

-   -   deciding of whether or not an interval between generation of a        first flow that is generated when performing radio communication        between a communication terminal and a base station and        generation of a second flow that is generated after the        generation of the first flow exceeds a permissible delay time of        the first flow; and    -   determination of deleting non-transmitted data related to the        communication terminal after lapse of the permissible delay time        of the first flow when it is decided that the generation        interval exceeds the permissible delay time of the first flow.

(Supplementary Note 17)

The program described in Supplementary note 16 for causing a computer toexecute measurement of the generation interval between the first flowand the second flow used in the judgment.

(Supplementary Note 18)

The program described in Supplementary note 16 or 17 for causing acomputer to re-decide whether or not the generation interval exceeds thepermissible delay time when at least one of the generation interval andthe permissible delay time of the first flow is changed.

(Supplementary Note 19)

The program described in any one of Supplementary notes 16 to 18 forcausing a computer to execute transmission, after it is determined thatthe non-transmitted data related to the communication terminal afterlapse of the permissible delay time of the first flow is deleted, ofinformation of the determination to the communication terminal and thebase station.

(Supplementary Note 20)

The program described in any one of Supplementary notes 16 to 18 forcausing a computer to execute deletion, after it is determined that thenon-transmitted data related to the communication terminal after lapseof the permissible delay time of the first flow is deleted, of thenon-transmitted data related to the communication terminal after lapseof the permissible delay time of the first flow.

REFERENCE SIGNS LIST

-   10 COMMUNICATION TERMINAL-   20 BASE STATION-   30 CONTROL DEVICE-   31 DECIDING UNIT-   32 DETERMINATION UNIT-   40 MEC SERVER-   41 COMMUNICATION UNIT-   42 MANAGEMENT UNIT-   50 UE-   60 eNB-   70 UE-   71 DECIDING UNIT-   72 DETERMINATION UNIT-   73 COMMUNICATION UNIT-   74 MANAGEMENT UNIT-   75 PROCESSING UNIT

What is claimed is:
 1. A control device comprising: at least one memorystoring instructions, and at least one processor configured to executethe instructions to; decide whether or not an interval betweengeneration of a first flow that is generated when performing radiocommunication between a communication terminal and a base station andgeneration of a second flow that is generated after the generation ofthe first flow exceeds a permissible delay time of the first flow; anddetermine to delete non-transmitted data related to the communicationterminal after lapse of the permissible delay time of the first flowwhen it is decided that the generation interval exceeds the permissibledelay time of the first flow.
 2. The control device according to claim1, wherein the at least one processor is further configured to executethe instructions to measure the generation interval.
 3. The controldevice according to claim 1, wherein the at least one processor isfurther configured to execute the instructions to manage informationrelated to permissible delay times of the first flow and the secondflow, and obtain the permissible delay time of the first flow.
 4. Thecontrol device according to claim 1, wherein the at least one processoris further configured to execute the instructions to determine deletionof data remaining in a buffer configured to store data included in thefirst flow and the second flow after lapse of the permissible delay timeof the first flow.
 5. The control device according to claim 1, whereinthe at least one processor is further configured to execute theinstructions to re-decide whether or not the generation interval exceedsthe permissible delay time when at least one of the generation intervaland the permissible delay time of the first flow is changed.
 6. Thecontrol device according to claim 1, wherein the at least one processoris further configured to execute the instructions to transmitinformation indicating that the non-transmitted data related to thecommunication terminal after lapse of the permissible delay time of thefirst flow is deleted to the communication terminal and the basestation.
 7. The control device according to claim 6, wherein the atleast one processor is further configured to execute the instructions totransmit the information indicating that the non-transmitted data isdeleted to the communication terminal, the destination of theinformation being the base station, and transmit the informationindicating that the non-transmitted data is deleted to the base station,the destination of the information being the communication terminal. 8.The control device according to claim 6, wherein the at least oneprocessor is further configured to execute the instructions to detectpresence of the non-transmitted data related to the communicationterminal after lapse of the permissible delay time of the first flow,and instruct the communication terminal or the base station that has thenon-transmitted data to delete the non-transmitted data.
 9. The controldevice according to claim 1, wherein the at least one processor isfurther configured to execute the instructions to delete thenon-transmitted data related to the communication terminal after lapseof the permissible delay time of the first flow.
 10. The control deviceaccording to claim 9, wherein the at least one processor is furtherconfigured to execute the instructions to delete the non-transmitteddata at a prescribed timing before lapse of the permissible delay timeof the first flow.
 11. A control method comprising: deciding whether ornot an interval between generation of a first flow that is generatedwhen performing radio communication between a communication terminal anda base station and generation of a second flow that is generated afterthe generation of the first flow exceeds a permissible delay time of thefirst flow; and determining to delete non-transmitted data related tothe communication terminal after lapse of the permissible delay time ofthe first flow when it is decided that the generation interval exceedsthe permissible delay time of the first flow.
 12. The control methodaccording to claim 11, further comprising measuring the generationinterval between the first flow and the second flow used in thedeciding.
 13. The control method according to claim 11, furthercomprising re-deciding whether or not the generation interval exceedsthe permissible delay time when at least one of the generation intervaland the permissible delay time of the first flow is changed.
 14. Thecontrol method according to claim 11, further comprising transmitting,after it is determined that the non-transmitted data related to thecommunication terminal after lapse of the permissible delay time of thefirst flow is deleted, information of the determination to thecommunication terminal and the base station.
 15. The control methodaccording to claim 11, further comprising deleting, after it isdetermined that the non-transmitted data related to the communicationterminal after lapse of the permissible delay time of the first flow isdeleted, the non-transmitted data related to the communication terminalafter lapse of the permissible delay time of the first flow.
 16. Anon-transitory computer readable media storing a program for causing acomputer to execute: deciding of whether or not an interval betweengeneration of a first flow that is generated when performing radiocommunication between a communication terminal and a base station andgeneration of a second flow that is generated after the generation ofthe first flow exceeds a permissible delay time of the first flow; anddetermination of deleting non-transmitted data related to thecommunication terminal after lapse of the permissible delay time of thefirst flow when it is decided that the generation interval exceeds thepermissible delay time of the first flow.
 17. The non-transitorycomputer readable media storing the program according to claim 16 forcausing a computer to execute measurement of the generation intervalbetween the first flow and the second flow used in the judgment.
 18. Thenon-transitory computer readable media storing the program according toclaim 16 for causing a computer to re-decide whether or not thegeneration interval exceeds the permissible delay time when at least oneof the generation interval and the permissible delay time of the firstflow is changed.
 19. The non-transitory computer readable media storingthe program according to claim 16 for causing a computer to executetransmission, after it is determined that the non-transmitted datarelated to the communication terminal after lapse of the permissibledelay time of the first flow is deleted, of information of thedetermination to the communication terminal and the base station. 20.The non-transitory computer readable media storing the program accordingto claim 16 for causing a computer to execute deletion, after it isdetermined that the non-transmitted data related to the communicationterminal after lapse of the permissible delay time of the first flow isdeleted, of the non-transmitted data related to the communicationterminal after lapse of the permissible delay time of the first flow.